1. Field of the Invention
The present invention relates to a rain sensor.
2. Description of the Related Art
Various rain sensors have been proposed which detect a rainfall based on raindrops adhering to the windshield of a vehicle. A device disclosed in Japanese Patent Application Laid-Open No. 2007-0127595 is employed in the rain sensor to be used as an device for detecting raindrops adhering to a windshield.
The device disclosed in Japanese Patent Application Laid-Open No. 2007-0127595 is configured such that a white member is provided on the surface of a windshield inside a vehicle compartment, the area of the windshield where the white member is provided is picked up by a camera outside the vehicle compartment and the picked up image is processed to detect the raindrops adhering to the windshield from the difference between a white portion and a peripheral landscape reflected by the adhering raindrops.
However, a raindrop can reflect a landscape around a vehicle, in particular, a pure white building. In such a case, the device disclosed in said Japanese Patent Application may not detect the part of the raindrop reflecting the landscape around the vehicle as the raindrop because the part thereof is not different from the white portion in processing the image.
The present invention is directed to enable a raindrop to be adequately detected in a picked-up image.